Conventionally, an adaptive cruise control system is developed that automatically adjusts a vehicle speed to control a following distance with a preceding vehicle by measuring the following distance with the preceding vehicle; further, a collision-warning and collision-mitigation system is developed that performs controls such as alarming or braking when a collision occurrence probability is high.
In these systems, detection accuracy has significant importance in recognition devices using a radar sensor or the like that recognizes a position, relative speed, and dimension of the detection object. Therefore, as described in Patent documents 1 to 5, a sensor fusion system is devised. This sensor fusion system includes multiple recognition devices such as a laser sensor recognition unit and an image sensor recognition unit using a camera. Here, the laser sensor recognition unit includes such as a radio-wave type milli-meter-wave radar or a laser radar using an infra-red laser. The detection results from the multiple recognition units are thereby combined to achieve higher accuracy and reliability.
For instance, in a forward-vehicle recognition device in Patent document 1, the radar recognition unit recognizes a following distance, orientation and relative speed, while the image sensor recognition unit recognizes a following distance, orientation, relative speed, vehicle width, and position within a lane. In a synthetic processing unit, when the detected following distances, orientations, relative speeds in the radar recognition unit and the image sensor recognition unit are equal therebetween, it is regarded that the same single vehicle is detected. This result is added to recognition results. Here, as the recognition result, the following distance, orientation and relative speed recognized in common by the radar recognition unit and image sensor recognition unit and the vehicle width and position within a lane recognized by the image sensor recognition unit are outputted by the synthetic processing unit.
Patent document 1: JP-2003-168197 A (US 2003/105578 A)
Patent document 2: JP-2003-151094 A (US 2003/0097237 A)
Patent document 3: JP-2003-84064 A
Patent document 4: JP-2003-172780 A
Patent document 5: JP-2003-99906 A
This type of synthetic processing unit is expected to be used in various vehicle types. Here, when the unit is used in the different vehicle types (luxury or public), different functions, different sensors, or different combinations of sensors may be required. Further, a sensor fusion system may be formed by combining various sensors, each of which is provided by a different vendor.
Here, this sensor fusion system potentially involves problems. Typically, the sensor fusion system includes various recognition means including sensors, and a final-staged synthetic determination processing being algorithm that collects and fuses the data outputs from the recognition means. This algorithm is thereby dedicated to the types or combination of the sensors. In other words, each time the combination of sensors or a specification of one of the recognition means is changed, the algorithm of the synthetic determination processing needs reexamining.
It is supposed that as a public-vehicle-oriented drive assist system, an adaptive cruise control system and lane-deviation alarm are mounted in a vehicle. Here, it is expected that a low-priced laser radar, low-resolution camera, and relatively low capability computation circuit constitute a low-priced recognition sensor unit for detecting white lanes and objects. In contrast, for a luxury vehicle, to enhance a function, it is expected that a collision-mitigation system or lane-keeping assist system is mounted in a vehicle. Here, a high environment-resistance milli-meter wave radar, high-resolution camera device having a dynamic range, and high capability computation circuit may constitute the recognition sensor unit for detecting white lanes and objects. Further, for a middle-class vehicle, a different combination having a slightly low capability and price may be adopted.
In this situation, if algorithm for the synthetic determination processing needs developing with respect to each of the combinations, the development cost will become high. Further, even when a recognition algorithm or the like that is a mere small part of the system is changed, the overall algorithm for data fusion must be reexamined.